ZXCM209 View Datasheet(PDF) - Zetex => Diodes
Part Name
Description
Manufacturer
ZXCM209 Datasheet PDF : 8 Pages
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ZXCM209
ZXCM210
APPLICATIONS INFORMATION
Negative going VCC transients
The ZXCM209/210 are, to a good degree, immune to
short duration negative going supply transients. Under
certain circumstances very brief transients are allowed
without inappropriate false triggering of the reset
circuit. The response to supply transients is shown in the
Noise Immunity graph in the typical characteristics. The
graph indicates the typical allowable transient duration
for a specified threshold overdrive such that a reset
pulse is not generated. Addition of a bypass capacitor,
e.g. 0.1µF, as close as possible to the VCC pin will provide
extra transient immunity.
Reset valid down to very low supply voltages
With VCC between 0V and 1V the output of the
ZXCM209/210 may be in an undefined state. In many
systems this is inconsequential as the
microprocessor, and other circuits, will be inoperative
with supplies this low. In applications where this is
important, the addition of an external resistor ensures
that the reset output remains valid for VCC < 1V. The
resistor value is non critical: a value of 100kΩ is
recommended. For the ZXCM209 the resistor should
be applied between reset output and ground: for the
ZXCM210 between reset output and VCC. Figure 1
shows the connection diagram for the ZXCM devices
in these configurations.
vcc
vcc
ZXCM209
Reset
Output
Gnd
vcc
Micro
Reset
Input
100k
Gnd
vcc
vcc
ZXCM210
Reset
Output
100k
vcc
Micro
Reset
Input
Gnd
Gnd
Figure 1
Circuit for operation of ZXCM with reset valid down to very low supply voltage.
ISSUE 3 - FEBRUARY 2001
5
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